diff --git a/conftest.py b/conftest.py
index 34ec38b..771f510 100644
--- a/conftest.py
+++ b/conftest.py
@@ -18,3 +18,18 @@ def collected_static_files():
         with override_settings(STATIC_ROOT=static_root):
             call_command('collectstatic', interactive=False, verbosity=0)
             yield
+
+
+@pytest.fixture(scope='session', autouse=True)
+def isolated_media_root():
+    """Los tests que suben imágenes (PatternImage, portada de Pattern...)
+    escriben de verdad en MEDIA_ROOT; sin aislarlo, se acumulan en la
+    carpeta media/ real del proyecto de una ejecución a otra, y como
+    cover_image.py guarda cada variante con un nombre fijo (thumbnail.jpg,
+    large.jpg) dentro de una carpeta por mes, esas sobras podían chocar con
+    los nombres que espera un test concreto (ver
+    PatternCoverImageUploadViewTests) y hacerlo fallar según lo que hubiera
+    quedado de ejecuciones anteriores."""
+    with tempfile.TemporaryDirectory() as media_root:
+        with override_settings(MEDIA_ROOT=media_root):
+            yield
diff --git a/crochet/cover_image.py b/crochet/cover_image.py
new file mode 100644
index 0000000..06c31b9
--- /dev/null
+++ b/crochet/cover_image.py
@@ -0,0 +1,52 @@
+import io
+
+from django.core.files.base import ContentFile
+from PIL import Image, UnidentifiedImageError
+
+# Miniatura para las tarjetas de "Mis patrones" (ver account_home.html) y
+# versión grande para una futura vista de detalle/producto: dos tamaños
+# cubren los usos actuales sin generar variantes de más.
+THUMBNAIL_MAX_SIZE = (400, 400)
+LARGE_MAX_SIZE = (1200, 1200)
+
+
+class InvalidCoverImage(Exception):
+    pass
+
+
+def _resized_jpeg(image, max_size):
+    resized = image.copy()
+    # thumbnail() redimensiona conservando el aspect ratio, sin salirse de
+    # la caja (max_size), a diferencia de resize() (que deformaría la
+    # imagen si no coincide con esa proporción).
+    resized.thumbnail(max_size, Image.Resampling.LANCZOS)
+    buffer = io.BytesIO()
+    resized.save(buffer, format='JPEG', quality=85, optimize=True)
+    return buffer.getvalue()
+
+
+def build_cover_image_variants(uploaded_file):
+    # Devuelve (original, thumbnail, large) como ContentFile, listos para
+    # asignar a cover_image/cover_image_thumbnail/cover_image_large.
+    raw_bytes = uploaded_file.read()
+    try:
+        image = Image.open(io.BytesIO(raw_bytes))
+        image.load()
+    except UnidentifiedImageError as error:
+        raise InvalidCoverImage('El archivo no es una imagen válida.') from error
+
+    # JPEG no admite transparencia: se aplana sobre fondo blanco antes de
+    # generar las variantes en vez de dejar que Pillow falle al guardar un
+    # PNG/RGBA como JPEG.
+    if image.mode in ('RGBA', 'LA', 'P'):
+        rgba = image.convert('RGBA')
+        flattened = Image.new('RGB', image.size, (255, 255, 255))
+        flattened.paste(rgba, mask=rgba.split()[-1])
+        image = flattened
+    else:
+        image = image.convert('RGB')
+
+    original = ContentFile(raw_bytes, name=uploaded_file.name)
+    thumbnail = ContentFile(_resized_jpeg(image, THUMBNAIL_MAX_SIZE), name='thumbnail.jpg')
+    large = ContentFile(_resized_jpeg(image, LARGE_MAX_SIZE), name='large.jpg')
+    return original, thumbnail, large
diff --git a/crochet/locale/en/LC_MESSAGES/django.po b/crochet/locale/en/LC_MESSAGES/django.po
index b873078..5d8dbc3 100644
--- a/crochet/locale/en/LC_MESSAGES/django.po
+++ b/crochet/locale/en/LC_MESSAGES/django.po
@@ -2,7 +2,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: crochet\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2026-07-17 11:03+0000\n"
+"POT-Creation-Date: 2026-07-17 11:17+0000\n"
 "Language: en\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
@@ -26,33 +26,33 @@ msgstr "Create pattern"
 msgid "¿Seguro que quieres eliminar este patrón? No podrás deshacerlo."
 msgstr "Are you sure you want to delete this pattern? This cannot be undone."
 
-#: crochet/templates/crochet/account_home.html:27
+#: crochet/templates/crochet/account_home.html:34
 msgid "Patrón sin título"
 msgstr "Untitled pattern"
 
-#: crochet/templates/crochet/account_home.html:30
+#: crochet/templates/crochet/account_home.html:37
 #, python-format
 msgid "Actualizado el %(date)s"
 msgstr "Updated on %(date)s"
 
-#: crochet/templates/crochet/account_home.html:33
+#: crochet/templates/crochet/account_home.html:40
 #: crochet/templates/crochet/pattern.html:34
 msgid "Ver patrón"
 msgstr "View pattern"
 
-#: crochet/templates/crochet/account_home.html:34
+#: crochet/templates/crochet/account_home.html:41
 msgid "Editar"
 msgstr "Edit"
 
-#: crochet/templates/crochet/account_home.html:38
+#: crochet/templates/crochet/account_home.html:45
 msgid "Eliminar"
 msgstr "Delete"
 
-#: crochet/templates/crochet/account_home.html:47
+#: crochet/templates/crochet/account_home.html:54
 msgid "Todavía no tienes ningún patrón."
 msgstr "You don't have any patterns yet."
 
-#: crochet/templates/crochet/account_home.html:53
+#: crochet/templates/crochet/account_home.html:60
 #: crochet/templates/crochet/base.html:34
 msgid "Cerrar sesión"
 msgstr "Log out"
@@ -110,184 +110,192 @@ msgid "Autor..."
 msgstr "Author..."
 
 #: crochet/templates/crochet/pattern.html:67
-#: crochet/templates/crochet/pattern.html:151
+msgid "Imagen de portada"
+msgstr "Cover image"
+
+#: crochet/templates/crochet/pattern.html:70
+msgid "No se ha podido subir la imagen de portada. Inténtalo de nuevo."
+msgstr "Couldn't upload the cover image. Please try again."
+
+#: crochet/templates/crochet/pattern.html:78
+#: crochet/templates/crochet/pattern.html:162
 msgid "Color del texto"
 msgstr "Text color"
 
-#: crochet/templates/crochet/pattern.html:71
+#: crochet/templates/crochet/pattern.html:82
 msgid "Color de acento (títulos)"
 msgstr "Accent color (headings)"
 
-#: crochet/templates/crochet/pattern.html:75
-#: crochet/templates/crochet/pattern.html:151
+#: crochet/templates/crochet/pattern.html:86
+#: crochet/templates/crochet/pattern.html:162
 msgid "Color de fondo"
 msgstr "Background color"
 
-#: crochet/templates/crochet/pattern.html:79
+#: crochet/templates/crochet/pattern.html:90
 msgid "Tipografía"
 msgstr "Font"
 
-#: crochet/templates/crochet/pattern.html:85
+#: crochet/templates/crochet/pattern.html:96
 msgid "Monoespaciada"
 msgstr "Monospace"
 
-#: crochet/templates/crochet/pattern.html:89
+#: crochet/templates/crochet/pattern.html:100
 msgid "Tamaño de letra"
 msgstr "Font size"
 
-#: crochet/templates/crochet/pattern.html:91
+#: crochet/templates/crochet/pattern.html:102
 msgid "Pequeño"
 msgstr "Small"
 
-#: crochet/templates/crochet/pattern.html:92
+#: crochet/templates/crochet/pattern.html:103
 msgid "Normal"
 msgstr "Normal"
 
-#: crochet/templates/crochet/pattern.html:93
+#: crochet/templates/crochet/pattern.html:104
 msgid "Grande"
 msgstr "Large"
 
-#: crochet/templates/crochet/pattern.html:97
+#: crochet/templates/crochet/pattern.html:108
 msgid "Alineación del texto"
 msgstr "Text alignment"
 
-#: crochet/templates/crochet/pattern.html:99
+#: crochet/templates/crochet/pattern.html:110
 msgid "Izquierda"
 msgstr "Left"
 
-#: crochet/templates/crochet/pattern.html:100
+#: crochet/templates/crochet/pattern.html:111
 msgid "Centrado"
 msgstr "Center"
 
-#: crochet/templates/crochet/pattern.html:101
+#: crochet/templates/crochet/pattern.html:112
 msgid "Justificado"
 msgstr "Justify"
 
-#: crochet/templates/crochet/pattern.html:105
+#: crochet/templates/crochet/pattern.html:116
 msgid "Tamaño de página"
 msgstr "Page size"
 
-#: crochet/templates/crochet/pattern.html:110
+#: crochet/templates/crochet/pattern.html:121
 msgid "Carta (Letter)"
 msgstr "Letter"
 
-#: crochet/templates/crochet/pattern.html:115
+#: crochet/templates/crochet/pattern.html:126
 msgid "Orientación"
 msgstr "Orientation"
 
-#: crochet/templates/crochet/pattern.html:117
+#: crochet/templates/crochet/pattern.html:128
 msgid "Vertical"
 msgstr "Portrait"
 
-#: crochet/templates/crochet/pattern.html:118
+#: crochet/templates/crochet/pattern.html:129
 msgid "Horizontal"
 msgstr "Landscape"
 
-#: crochet/templates/crochet/pattern.html:126
-#: crochet/templates/crochet/pattern.html:134
+#: crochet/templates/crochet/pattern.html:137
+#: crochet/templates/crochet/pattern.html:145
 msgid "Secciones"
 msgstr "Sections"
 
-#: crochet/templates/crochet/pattern.html:127
-#: crochet/templates/crochet/pattern.html:173
+#: crochet/templates/crochet/pattern.html:138
+#: crochet/templates/crochet/pattern.html:184
 msgid "Vista previa"
 msgstr "Preview"
 
-#: crochet/templates/crochet/pattern.html:136
+#: crochet/templates/crochet/pattern.html:147
 msgid "Colapsar todo"
 msgstr "Collapse all"
 
-#: crochet/templates/crochet/pattern.html:136
+#: crochet/templates/crochet/pattern.html:147
 msgid "Expandir todo"
 msgstr "Expand all"
 
-#: crochet/templates/crochet/pattern.html:141
+#: crochet/templates/crochet/pattern.html:152
 msgid "Añadir sección"
 msgstr "Add section"
 
-#: crochet/templates/crochet/pattern.html:144
+#: crochet/templates/crochet/pattern.html:155
 msgid "Título"
 msgstr "Title"
 
-#: crochet/templates/crochet/pattern.html:144
+#: crochet/templates/crochet/pattern.html:155
 msgid "Título..."
 msgstr "Title..."
 
-#: crochet/templates/crochet/pattern.html:146
+#: crochet/templates/crochet/pattern.html:157
 msgid "Subtítulo"
 msgstr "Subtitle"
 
-#: crochet/templates/crochet/pattern.html:146
+#: crochet/templates/crochet/pattern.html:157
 msgid "Subtítulo..."
 msgstr "Subtitle..."
 
-#: crochet/templates/crochet/pattern.html:148
+#: crochet/templates/crochet/pattern.html:159
 msgid "Texto"
 msgstr "Text"
 
-#: crochet/templates/crochet/pattern.html:148
+#: crochet/templates/crochet/pattern.html:159
 msgid "Escribe aquí..."
 msgstr "Write here..."
 
-#: crochet/templates/crochet/pattern.html:150
-#: crochet/templates/crochet/pattern.html:151
+#: crochet/templates/crochet/pattern.html:161
+#: crochet/templates/crochet/pattern.html:162
 msgid "Nota"
 msgstr "Note"
 
-#: crochet/templates/crochet/pattern.html:150
+#: crochet/templates/crochet/pattern.html:161
 msgid "Escribe una nota o consejo..."
 msgstr "Write a note or tip..."
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Materiales"
 msgstr "Materials"
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Añadir material..."
 msgstr "Add material..."
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Añadir línea"
 msgstr "Add line"
 
-#: crochet/templates/crochet/pattern.html:155
-#: crochet/templates/crochet/pattern.html:157
+#: crochet/templates/crochet/pattern.html:166
+#: crochet/templates/crochet/pattern.html:168
 msgid "Imagen"
 msgstr "Image"
 
-#: crochet/templates/crochet/pattern.html:157
+#: crochet/templates/crochet/pattern.html:168
 msgid "No se ha podido subir la imagen. Inténtalo de nuevo."
 msgstr "Couldn't upload the image. Please try again."
 
-#: crochet/templates/crochet/pattern.html:159
+#: crochet/templates/crochet/pattern.html:170
 msgid "Patrón"
 msgstr "Pattern"
 
-#: crochet/templates/crochet/pattern.html:159
+#: crochet/templates/crochet/pattern.html:170
 msgid "Elementos"
 msgstr "Elements"
 
-#: crochet/templates/crochet/pattern.html:161
+#: crochet/templates/crochet/pattern.html:172
 msgid "Grupo"
 msgstr "Group"
 
-#: crochet/templates/crochet/pattern.html:165
+#: crochet/templates/crochet/pattern.html:176
 msgid "Arrastrar para reordenar"
 msgstr "Drag to reorder"
 
-#: crochet/templates/crochet/pattern.html:166
+#: crochet/templates/crochet/pattern.html:177
 msgid "Colapsar / expandir"
 msgstr "Collapse / expand"
 
-#: crochet/templates/crochet/pattern.html:167
+#: crochet/templates/crochet/pattern.html:178
 msgid "Duplicar sección"
 msgstr "Duplicate section"
 
-#: crochet/templates/crochet/pattern.html:168
+#: crochet/templates/crochet/pattern.html:179
 msgid "Eliminar sección"
 msgstr "Delete section"
 
-#: crochet/templates/crochet/pattern.html:169
+#: crochet/templates/crochet/pattern.html:180
 msgid ""
 "¿Seguro que quieres eliminar este grupo? Se eliminarán también todas las "
 "secciones que contiene."
@@ -295,7 +303,7 @@ msgstr ""
 "Are you sure you want to delete this group? All sections inside it will also "
 "be deleted."
 
-#: crochet/templates/crochet/pattern.html:175
+#: crochet/templates/crochet/pattern.html:186
 msgid "Añade una sección para ver aquí el resultado."
 msgstr "Add a section to see the result here."
 
@@ -324,51 +332,55 @@ msgstr "Create account"
 msgid "¿Ya tienes cuenta? Inicia sesión"
 msgstr "Already have an account? Log in"
 
-#: crochet/urls.py:30
+#: crochet/urls.py:31
 msgid "pattern/<uuid:uuid>/"
 msgstr ""
 
-#: crochet/urls.py:31
+#: crochet/urls.py:32
 msgid "pattern/<uuid:uuid>/edit/"
 msgstr ""
 
-#: crochet/urls.py:32
+#: crochet/urls.py:33
 msgid "pattern/<uuid:uuid>/save/"
 msgstr ""
 
-#: crochet/urls.py:33
+#: crochet/urls.py:34
 msgid "pattern/<uuid:uuid>/images/"
 msgstr ""
 
-#: crochet/urls.py:34
-msgid "pattern/<uuid:uuid>/pdf/"
-msgstr ""
-
 #: crochet/urls.py:35
-msgid "pattern/<uuid:uuid>/delete/"
+msgid "pattern/<uuid:uuid>/cover/"
 msgstr ""
 
 #: crochet/urls.py:36
-msgid "pattern/new/"
+msgid "pattern/<uuid:uuid>/pdf/"
 msgstr ""
 
 #: crochet/urls.py:37
-msgid "account/"
+msgid "pattern/<uuid:uuid>/delete/"
 msgstr ""
 
 #: crochet/urls.py:38
-msgid "account/register/"
+msgid "pattern/new/"
+msgstr ""
+
+#: crochet/urls.py:39
+msgid "account/"
 msgstr ""
 
 #: crochet/urls.py:40
+msgid "account/register/"
+msgstr ""
+
+#: crochet/urls.py:42
 msgid "account/login/"
 msgstr ""
 
-#: crochet/urls.py:45
+#: crochet/urls.py:47
 msgid "account/logout/"
 msgstr ""
 
 # crochet/views.py (PatternDetailView.EMPTY_MESSAGE)
-#: crochet/views.py:23
+#: crochet/views.py:24
 msgid "Este patrón todavía no tiene contenido."
 msgstr "This pattern doesn't have any content yet."
diff --git a/crochet/locale/es/LC_MESSAGES/django.po b/crochet/locale/es/LC_MESSAGES/django.po
index 4d676ec..f71cfe1 100644
--- a/crochet/locale/es/LC_MESSAGES/django.po
+++ b/crochet/locale/es/LC_MESSAGES/django.po
@@ -2,7 +2,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: crochet\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2026-07-17 11:03+0000\n"
+"POT-Creation-Date: 2026-07-17 11:17+0000\n"
 "Language: es\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
@@ -26,33 +26,33 @@ msgstr ""
 msgid "¿Seguro que quieres eliminar este patrón? No podrás deshacerlo."
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:27
+#: crochet/templates/crochet/account_home.html:34
 msgid "Patrón sin título"
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:30
+#: crochet/templates/crochet/account_home.html:37
 #, python-format
 msgid "Actualizado el %(date)s"
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:33
+#: crochet/templates/crochet/account_home.html:40
 #: crochet/templates/crochet/pattern.html:34
 msgid "Ver patrón"
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:34
+#: crochet/templates/crochet/account_home.html:41
 msgid "Editar"
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:38
+#: crochet/templates/crochet/account_home.html:45
 msgid "Eliminar"
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:47
+#: crochet/templates/crochet/account_home.html:54
 msgid "Todavía no tienes ningún patrón."
 msgstr ""
 
-#: crochet/templates/crochet/account_home.html:53
+#: crochet/templates/crochet/account_home.html:60
 #: crochet/templates/crochet/base.html:34
 msgid "Cerrar sesión"
 msgstr ""
@@ -109,190 +109,198 @@ msgid "Autor..."
 msgstr ""
 
 #: crochet/templates/crochet/pattern.html:67
-#: crochet/templates/crochet/pattern.html:151
+msgid "Imagen de portada"
+msgstr ""
+
+#: crochet/templates/crochet/pattern.html:70
+msgid "No se ha podido subir la imagen de portada. Inténtalo de nuevo."
+msgstr ""
+
+#: crochet/templates/crochet/pattern.html:78
+#: crochet/templates/crochet/pattern.html:162
 msgid "Color del texto"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:71
+#: crochet/templates/crochet/pattern.html:82
 msgid "Color de acento (títulos)"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:75
-#: crochet/templates/crochet/pattern.html:151
+#: crochet/templates/crochet/pattern.html:86
+#: crochet/templates/crochet/pattern.html:162
 msgid "Color de fondo"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:79
+#: crochet/templates/crochet/pattern.html:90
 msgid "Tipografía"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:85
+#: crochet/templates/crochet/pattern.html:96
 msgid "Monoespaciada"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:89
+#: crochet/templates/crochet/pattern.html:100
 msgid "Tamaño de letra"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:91
+#: crochet/templates/crochet/pattern.html:102
 msgid "Pequeño"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:92
+#: crochet/templates/crochet/pattern.html:103
 msgid "Normal"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:93
+#: crochet/templates/crochet/pattern.html:104
 msgid "Grande"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:97
+#: crochet/templates/crochet/pattern.html:108
 msgid "Alineación del texto"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:99
+#: crochet/templates/crochet/pattern.html:110
 msgid "Izquierda"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:100
+#: crochet/templates/crochet/pattern.html:111
 msgid "Centrado"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:101
+#: crochet/templates/crochet/pattern.html:112
 msgid "Justificado"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:105
+#: crochet/templates/crochet/pattern.html:116
 msgid "Tamaño de página"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:110
+#: crochet/templates/crochet/pattern.html:121
 msgid "Carta (Letter)"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:115
+#: crochet/templates/crochet/pattern.html:126
 msgid "Orientación"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:117
+#: crochet/templates/crochet/pattern.html:128
 msgid "Vertical"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:118
+#: crochet/templates/crochet/pattern.html:129
 msgid "Horizontal"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:126
-#: crochet/templates/crochet/pattern.html:134
+#: crochet/templates/crochet/pattern.html:137
+#: crochet/templates/crochet/pattern.html:145
 msgid "Secciones"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:127
-#: crochet/templates/crochet/pattern.html:173
+#: crochet/templates/crochet/pattern.html:138
+#: crochet/templates/crochet/pattern.html:184
 msgid "Vista previa"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:136
+#: crochet/templates/crochet/pattern.html:147
 msgid "Colapsar todo"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:136
+#: crochet/templates/crochet/pattern.html:147
 msgid "Expandir todo"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:141
+#: crochet/templates/crochet/pattern.html:152
 msgid "Añadir sección"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:144
+#: crochet/templates/crochet/pattern.html:155
 msgid "Título"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:144
+#: crochet/templates/crochet/pattern.html:155
 msgid "Título..."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:146
+#: crochet/templates/crochet/pattern.html:157
 msgid "Subtítulo"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:146
+#: crochet/templates/crochet/pattern.html:157
 msgid "Subtítulo..."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:148
+#: crochet/templates/crochet/pattern.html:159
 msgid "Texto"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:148
+#: crochet/templates/crochet/pattern.html:159
 msgid "Escribe aquí..."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:150
-#: crochet/templates/crochet/pattern.html:151
+#: crochet/templates/crochet/pattern.html:161
+#: crochet/templates/crochet/pattern.html:162
 msgid "Nota"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:150
+#: crochet/templates/crochet/pattern.html:161
 msgid "Escribe una nota o consejo..."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Materiales"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Añadir material..."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:153
+#: crochet/templates/crochet/pattern.html:164
 msgid "Añadir línea"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:155
-#: crochet/templates/crochet/pattern.html:157
+#: crochet/templates/crochet/pattern.html:166
+#: crochet/templates/crochet/pattern.html:168
 msgid "Imagen"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:157
+#: crochet/templates/crochet/pattern.html:168
 msgid "No se ha podido subir la imagen. Inténtalo de nuevo."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:159
+#: crochet/templates/crochet/pattern.html:170
 msgid "Patrón"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:159
+#: crochet/templates/crochet/pattern.html:170
 msgid "Elementos"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:161
+#: crochet/templates/crochet/pattern.html:172
 msgid "Grupo"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:165
+#: crochet/templates/crochet/pattern.html:176
 msgid "Arrastrar para reordenar"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:166
+#: crochet/templates/crochet/pattern.html:177
 msgid "Colapsar / expandir"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:167
+#: crochet/templates/crochet/pattern.html:178
 msgid "Duplicar sección"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:168
+#: crochet/templates/crochet/pattern.html:179
 msgid "Eliminar sección"
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:169
+#: crochet/templates/crochet/pattern.html:180
 msgid ""
 "¿Seguro que quieres eliminar este grupo? Se eliminarán también todas las "
 "secciones que contiene."
 msgstr ""
 
-#: crochet/templates/crochet/pattern.html:175
+#: crochet/templates/crochet/pattern.html:186
 msgid "Añade una sección para ver aquí el resultado."
 msgstr ""
 
@@ -323,51 +331,55 @@ msgstr ""
 
 # Rutas traducibles de crochet/urls.py: la base "pattern/" se traduce como
 # "patron/" (sin tilde, para no meter caracteres acentuados en la URL).
-#: crochet/urls.py:30
+#: crochet/urls.py:31
 msgid "pattern/<uuid:uuid>/"
 msgstr "patron/<uuid:uuid>/"
 
-#: crochet/urls.py:31
+#: crochet/urls.py:32
 msgid "pattern/<uuid:uuid>/edit/"
 msgstr "patron/<uuid:uuid>/editar/"
 
-#: crochet/urls.py:32
+#: crochet/urls.py:33
 msgid "pattern/<uuid:uuid>/save/"
 msgstr "patron/<uuid:uuid>/guardar/"
 
-#: crochet/urls.py:33
+#: crochet/urls.py:34
 msgid "pattern/<uuid:uuid>/images/"
 msgstr "patron/<uuid:uuid>/imagenes/"
 
-#: crochet/urls.py:34
+#: crochet/urls.py:35
+msgid "pattern/<uuid:uuid>/cover/"
+msgstr "patron/<uuid:uuid>/portada/"
+
+#: crochet/urls.py:36
 msgid "pattern/<uuid:uuid>/pdf/"
 msgstr "patron/<uuid:uuid>/pdf/"
 
-#: crochet/urls.py:35
+#: crochet/urls.py:37
 msgid "pattern/<uuid:uuid>/delete/"
 msgstr "patron/<uuid:uuid>/eliminar/"
 
-#: crochet/urls.py:36
+#: crochet/urls.py:38
 msgid "pattern/new/"
 msgstr "patron/nuevo/"
 
 # Igual que "pattern/" arriba: "account/" se traduce como "cuenta/".
-#: crochet/urls.py:37
+#: crochet/urls.py:39
 msgid "account/"
 msgstr "cuenta/"
 
-#: crochet/urls.py:38
+#: crochet/urls.py:40
 msgid "account/register/"
 msgstr "cuenta/registro/"
 
-#: crochet/urls.py:40
+#: crochet/urls.py:42
 msgid "account/login/"
 msgstr "cuenta/entrar/"
 
-#: crochet/urls.py:45
+#: crochet/urls.py:47
 msgid "account/logout/"
 msgstr "cuenta/salir/"
 
-#: crochet/views.py:23
+#: crochet/views.py:24
 msgid "Este patrón todavía no tiene contenido."
 msgstr ""
diff --git a/crochet/migrations/0007_pattern_cover_image.py b/crochet/migrations/0007_pattern_cover_image.py
new file mode 100644
index 0000000..ff5f5fc
--- /dev/null
+++ b/crochet/migrations/0007_pattern_cover_image.py
@@ -0,0 +1,28 @@
+# Generated by Django 6.0.7 on 2026-07-17 11:15
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('crochet', '0006_pattern_created_by'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='pattern',
+            name='cover_image',
+            field=models.ImageField(blank=True, null=True, upload_to='patterns/covers/originals/%Y/%m/'),
+        ),
+        migrations.AddField(
+            model_name='pattern',
+            name='cover_image_large',
+            field=models.ImageField(blank=True, editable=False, null=True, upload_to='patterns/covers/large/%Y/%m/'),
+        ),
+        migrations.AddField(
+            model_name='pattern',
+            name='cover_image_thumbnail',
+            field=models.ImageField(blank=True, editable=False, null=True, upload_to='patterns/covers/thumbnails/%Y/%m/'),
+        ),
+    ]
diff --git a/crochet/models.py b/crochet/models.py
index fb3ed8a..7adb303 100644
--- a/crochet/models.py
+++ b/crochet/models.py
@@ -22,6 +22,20 @@ class Pattern(models.Model):
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)
 
+    # Portada del patrón: cover_image guarda el archivo tal cual lo sube el
+    # usuario; cover_image_thumbnail/cover_image_large son las variantes
+    # redimensionadas (ver crochet/cover_image.py) que se muestran de verdad
+    # en la web (tarjetas de "Mis patrones", futura vista de detalle...), no
+    # editable=False porque las genera PatternCoverImageUploadView, no un
+    # formulario.
+    cover_image = models.ImageField(upload_to='patterns/covers/originals/%Y/%m/', blank=True, null=True)
+    cover_image_thumbnail = models.ImageField(
+        upload_to='patterns/covers/thumbnails/%Y/%m/', blank=True, null=True, editable=False,
+    )
+    cover_image_large = models.ImageField(
+        upload_to='patterns/covers/large/%Y/%m/', blank=True, null=True, editable=False,
+    )
+
     def __str__(self):
         return self.page_settings.get('title') or str(self.uuid)
 
diff --git a/crochet/pattern_render.py b/crochet/pattern_render.py
index f6b2555..cfc749e 100644
--- a/crochet/pattern_render.py
+++ b/crochet/pattern_render.py
@@ -138,18 +138,22 @@ def _render_section(section, lang, stitch_types_by_id):
     return ''
 
 
-def render_pattern_html(sections, page_settings, lang, stitch_types, empty_message):
+def render_pattern_html(sections, page_settings, lang, stitch_types, empty_message, cover_image_url=None):
     """HTML (ya escapado y marcado como seguro) del contenido de un patrón
     para `lang`, en el mismo formato que genera renderOutput() en el
-    editor: título/autor del documento primero, y luego cada sección de
-    nivel superior en orden. `page_settings` debe venir ya validado por
-    sanitize_page_settings()."""
+    editor: título, portada y autor del documento primero, y luego cada
+    sección de nivel superior en orden. `page_settings` debe venir ya
+    validado por sanitize_page_settings()."""
     stitch_types_by_id = {st['id']: st for st in stitch_types}
 
-    parts = [
-        _line('h1', page_settings['title'], 'text-[1.5em] font-bold mb-1'),
-        _line('p', page_settings['author'], 'text-[0.875em] opacity-70 mb-2'),
-    ]
+    parts = [_line('h1', page_settings['title'], 'text-[1.5em] font-bold mb-1')]
+    # Mismas clases que _render_image() (misma pinta que una imagen de
+    # sección) y que la portada que pinta render.js en el editor.
+    if cover_image_url:
+        parts.append(format_html(
+            '<img src="{0}" class="max-w-full max-h-96 object-contain rounded-2xl my-2" alt="">', cover_image_url,
+        ))
+    parts.append(_line('p', page_settings['author'], 'text-[0.875em] opacity-70 mb-2'))
 
     if not sections:
         parts.append(format_html('<p class="opacity-50 italic">{0}</p>', empty_message))
diff --git a/crochet/static/js/cover-image.js b/crochet/static/js/cover-image.js
new file mode 100644
index 0000000..64dcb14
--- /dev/null
+++ b/crochet/static/js/cover-image.js
@@ -0,0 +1,36 @@
+// Subida de la portada del patrón (ver "Personalización de página" en
+// pattern.html). Distinto de sections.js (esa sube imágenes DENTRO de una
+// sección de tipo "Imagen"): esto es un atributo del patrón entero, así que
+// se sube y aplica en cuanto se elige el archivo, sin esperar a "Guardar".
+
+import { coverImageInput, coverImageLargeUrlInput, coverImagePreview } from './dom-refs.js';
+import { getCsrfToken } from './csrf.js';
+import { renderOutput } from './render.js';
+
+coverImageInput.addEventListener('change', async () => {
+  const file = coverImageInput.files[0];
+  if (!file) return;
+
+  const formData = new FormData();
+  formData.append('cover_image', file);
+
+  try {
+    const response = await fetch(coverImageInput.dataset.uploadUrl, {
+      method: 'POST',
+      headers: { 'X-CSRFToken': getCsrfToken() },
+      body: formData,
+    });
+    if (!response.ok) throw new Error(`HTTP ${response.status}`);
+
+    const data = await response.json();
+    coverImagePreview.src = data.thumbnailUrl;
+    coverImagePreview.classList.remove('hidden');
+    // "Vista previa" (ver render.js) pinta la portada a partir de este
+    // valor, igual que lee pageTitleInput/pageAuthorInput.
+    coverImageLargeUrlInput.value = data.largeUrl;
+    renderOutput();
+  } catch (error) {
+    console.error('No se ha podido subir la imagen de portada:', error);
+    alert(coverImageInput.dataset.errorMessage);
+  }
+});
diff --git a/crochet/static/js/dom-refs.js b/crochet/static/js/dom-refs.js
index 1c8aa7c..ca5cb43 100644
--- a/crochet/static/js/dom-refs.js
+++ b/crochet/static/js/dom-refs.js
@@ -22,3 +22,9 @@ export const pageAlignSelect = document.getElementById('page-align-select');
 export const pageSizeSelect = document.getElementById('page-size-select');
 export const pageOrientationSelect = document.getElementById('page-orientation-select');
 export const pageSizeStyle = document.getElementById('page-size-style');
+
+// Portada del patrón (ver cover-image.js): configuración del documento
+// entero, igual que título/autor de arriba, no una sección más.
+export const coverImageInput = document.getElementById('cover-image-input');
+export const coverImagePreview = document.getElementById('cover-image-preview'); // Miniatura dentro del propio control de subida.
+export const coverImageLargeUrlInput = document.getElementById('cover-image-large-url'); // Leído por render.js para "Vista previa".
diff --git a/crochet/static/js/main.js b/crochet/static/js/main.js
index 34caf10..cef1e3c 100644
--- a/crochet/static/js/main.js
+++ b/crochet/static/js/main.js
@@ -8,6 +8,7 @@ import { applyDefaultSkeleton, buildSectionsFrom } from './section-types.js';
 import { setAllSectionsCollapsed } from './sections.js';
 import './tabs.js';
 import './storage.js';
+import './cover-image.js';
 
 // Mismo punto de corte que .panel-hidden-mobile (ver css/main.css).
 const MOBILE_BREAKPOINT_QUERY = '(max-width: 767px)';
diff --git a/crochet/static/js/render.js b/crochet/static/js/render.js
index f5e3f1c..e6d83f1 100644
--- a/crochet/static/js/render.js
+++ b/crochet/static/js/render.js
@@ -3,7 +3,7 @@
 // repintarlo: al escribir, al cambiar de idioma, o al añadir/quitar/
 // reordenar secciones o elementos soltados.
 
-import { outputText, sectionsContainer, pageTitleInput, pageAuthorInput } from './dom-refs.js';
+import { outputText, sectionsContainer, pageTitleInput, pageAuthorInput, coverImageLargeUrlInput } from './dom-refs.js';
 import { TRANSLATABLE_FIELDS_SELECTOR, setTranslation, setupLanguageSelect } from './i18n.js';
 import { renderOutputSection, appendOutputLine } from './section-types.js';
 
@@ -12,13 +12,25 @@ import { renderOutputSection, appendOutputLine } from './section-types.js';
 export function renderOutput() {
   outputText.innerHTML = '';
 
-  // Título y autor del patrón (ver "Personalización de página"): son
-  // configuración de todo el documento, no una sección más, así que se
+  // Título, portada y autor del patrón (ver "Personalización de página"):
+  // son configuración de todo el documento, no una sección más, así que se
   // pintan siempre delante, haya o no secciones añadidas.
   // Tamaños en "em" (no las clases normales de Tailwind, en "rem") para que
   // escalen con el "Tamaño de letra" de #panel-output-text (ver
   // page-config.js): "rem" ignora el font-size de cualquier ancestro.
   appendOutputLine(outputText, 'h1', pageTitleInput.value.trim(), 'text-[1.5em] font-bold mb-1');
+
+  // Debajo del título: mismo tamaño "large" y mismas clases que pinta
+  // render_pattern_html() en la vista de solo lectura/PDF, para que ambos
+  // resultados sean visualmente idénticos (ver pattern_render.py).
+  if (coverImageLargeUrlInput.value) {
+    const coverImage = document.createElement('img');
+    coverImage.src = coverImageLargeUrlInput.value;
+    coverImage.alt = '';
+    coverImage.className = 'max-w-full max-h-96 object-contain rounded-2xl my-2';
+    outputText.appendChild(coverImage);
+  }
+
   appendOutputLine(outputText, 'p', pageAuthorInput.value.trim(), 'text-[0.875em] opacity-70 mb-2');
 
   // Si aún no se ha añadido ninguna sección, avisar en vez de dejar el
diff --git a/crochet/templates/crochet/account_home.html b/crochet/templates/crochet/account_home.html
index 648b423..e98401b 100644
--- a/crochet/templates/crochet/account_home.html
+++ b/crochet/templates/crochet/account_home.html
@@ -22,6 +22,13 @@
       <div class="grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
         {% for pattern in patterns %}
           <div class="card bg-base-100 shadow border border-base-300">
+            <figure class="h-40 bg-base-200">
+              {% if pattern.cover_image_thumbnail %}
+                <img src="{{ pattern.cover_image_thumbnail.url }}" alt="" class="w-full h-full object-cover">
+              {% else %}
+                <span class="text-4xl">🧶</span>
+              {% endif %}
+            </figure>
             <div class="card-body">
               <h2 class="card-title text-lg">
                 {% if pattern.page_settings.title %}{{ pattern.page_settings.title }}{% else %}{% trans 'Patrón sin título' %}{% endif %}
diff --git a/crochet/templates/crochet/pattern.html b/crochet/templates/crochet/pattern.html
index b98e88c..a7bfed1 100644
--- a/crochet/templates/crochet/pattern.html
+++ b/crochet/templates/crochet/pattern.html
@@ -62,6 +62,23 @@
               <input id="page-author-input" type="text" class="input input-bordered" placeholder="{% trans 'Autor...' %}">
             </label>
           </div>
+          <div class="flex items-end gap-4">
+            <label class="flex flex-col gap-1 flex-1">
+              <span class="text-sm">{% trans 'Imagen de portada' %}</span>
+              <input id="cover-image-input" type="file" accept="image/*" class="file-input file-input-bordered"
+                data-upload-url="{% url 'crochet:pattern_cover_upload' pattern.uuid %}"
+                data-error-message="{% trans 'No se ha podido subir la imagen de portada. Inténtalo de nuevo.' %}">
+            </label>
+            <img id="cover-image-preview" alt=""
+              src="{% if pattern.cover_image_thumbnail %}{{ pattern.cover_image_thumbnail.url }}{% endif %}"
+              class="w-24 h-24 object-cover rounded-box border border-base-300{% if not pattern.cover_image_thumbnail %} hidden{% endif %}">
+            <!-- Tamaño "large" (no el thumbnail de arriba, pensado solo
+                 para ese control): lo lee render.js para pintarla en
+                 "Vista previa", debajo del título, igual que hace
+                 render_pattern_html() en la vista de solo lectura/PDF. -->
+            <input type="hidden" id="cover-image-large-url"
+              value="{% if pattern.cover_image_large %}{{ pattern.cover_image_large.url }}{% endif %}">
+          </div>
           <div class="flex flex-wrap items-end gap-4">
             <label class="flex flex-col gap-1">
               <span class="text-sm">{% trans 'Color del texto' %}</span>
diff --git a/crochet/tests/test_cover_image.py b/crochet/tests/test_cover_image.py
new file mode 100644
index 0000000..eb3f6df
--- /dev/null
+++ b/crochet/tests/test_cover_image.py
@@ -0,0 +1,60 @@
+import io
+
+from django.core.files.uploadedfile import SimpleUploadedFile
+from django.test import SimpleTestCase
+from PIL import Image
+
+from crochet.cover_image import InvalidCoverImage, LARGE_MAX_SIZE, THUMBNAIL_MAX_SIZE, build_cover_image_variants
+
+
+def make_image_file(size=(2000, 1000), mode='RGB', color='red', name='cover.png', format='PNG'):
+    buffer = io.BytesIO()
+    Image.new(mode, size, color=color).save(buffer, format=format)
+    return SimpleUploadedFile(name, buffer.getvalue(), content_type=f'image/{format.lower()}')
+
+
+class BuildCoverImageVariantsTests(SimpleTestCase):
+    def test_thumbnail_and_large_fit_within_max_size(self):
+        original, thumbnail, large = build_cover_image_variants(make_image_file(size=(2000, 1000)))
+
+        thumbnail_image = Image.open(io.BytesIO(thumbnail.read()))
+        large_image = Image.open(io.BytesIO(large.read()))
+
+        self.assertLessEqual(thumbnail_image.width, THUMBNAIL_MAX_SIZE[0])
+        self.assertLessEqual(thumbnail_image.height, THUMBNAIL_MAX_SIZE[1])
+        self.assertLessEqual(large_image.width, LARGE_MAX_SIZE[0])
+        self.assertLessEqual(large_image.height, LARGE_MAX_SIZE[1])
+
+    def test_preserves_aspect_ratio(self):
+        _, thumbnail, _ = build_cover_image_variants(make_image_file(size=(2000, 1000)))
+        thumbnail_image = Image.open(io.BytesIO(thumbnail.read()))
+
+        self.assertAlmostEqual(thumbnail_image.width / thumbnail_image.height, 2.0, places=1)
+
+    def test_small_image_is_not_upscaled(self):
+        _, thumbnail, _ = build_cover_image_variants(make_image_file(size=(50, 50)))
+        thumbnail_image = Image.open(io.BytesIO(thumbnail.read()))
+
+        self.assertEqual(thumbnail_image.size, (50, 50))
+
+    def test_original_is_kept_unprocessed(self):
+        original, _, _ = build_cover_image_variants(make_image_file(size=(50, 50), name='mine.png'))
+
+        self.assertEqual(original.name, 'mine.png')
+        original_image = Image.open(io.BytesIO(original.read()))
+        self.assertEqual(original_image.size, (50, 50))
+
+    def test_transparent_png_is_flattened_for_jpeg_variants(self):
+        # Si el aplanado a RGB no funcionase, Pillow lanzaría un error al
+        # intentar guardar un canal alfa como JPEG (ver build_cover_image_variants).
+        uploaded = make_image_file(size=(50, 50), mode='RGBA', color=(255, 0, 0, 0))
+        _, thumbnail, large = build_cover_image_variants(uploaded)
+
+        self.assertEqual(Image.open(io.BytesIO(thumbnail.read())).mode, 'RGB')
+        self.assertEqual(Image.open(io.BytesIO(large.read())).mode, 'RGB')
+
+    def test_invalid_file_raises(self):
+        invalid_file = SimpleUploadedFile('not-an-image.png', b'this is not an image', content_type='image/png')
+
+        with self.assertRaises(InvalidCoverImage):
+            build_cover_image_variants(invalid_file)
diff --git a/crochet/tests/test_pattern_render.py b/crochet/tests/test_pattern_render.py
index 2e722a1..58bb440 100644
--- a/crochet/tests/test_pattern_render.py
+++ b/crochet/tests/test_pattern_render.py
@@ -74,13 +74,14 @@ class SanitizePageSettingsTests(SimpleTestCase):
 
 
 class RenderPatternHtmlTests(SimpleTestCase):
-    def render(self, sections, lang='es', stitch_types=None, page_settings=None):
+    def render(self, sections, lang='es', stitch_types=None, page_settings=None, cover_image_url=None):
         return render_pattern_html(
             sections,
             page_settings or DEFAULT_PAGE_SETTINGS,
             lang,
             stitch_types or [],
             'Este patrón todavía no tiene contenido.',
+            cover_image_url=cover_image_url,
         )
 
     def test_empty_sections_shows_empty_message(self):
@@ -92,6 +93,25 @@ class RenderPatternHtmlTests(SimpleTestCase):
         self.assertIn('<h1 class="text-[1.5em] font-bold mb-1">Ampharos</h1>', html)
         self.assertIn('<p class="text-[0.875em] opacity-70 mb-2">Nerea</p>', html)
 
+    def test_cover_image_renders_between_title_and_author(self):
+        html = self.render(
+            [], page_settings=sanitize_page_settings({'title': 'Ampharos', 'author': 'Nerea'}),
+            cover_image_url='/media/patterns/covers/large/2026/07/large.jpg',
+        )
+        title_index = html.index('Ampharos')
+        image_index = html.index('<img src="/media/patterns/covers/large/2026/07/large.jpg"')
+        author_index = html.index('Nerea')
+        self.assertLess(title_index, image_index)
+        self.assertLess(image_index, author_index)
+
+    def test_no_cover_image_renders_no_img_tag(self):
+        html = self.render([], cover_image_url=None)
+        self.assertNotIn('<img', html)
+
+    def test_cover_image_url_is_escaped(self):
+        html = self.render([], cover_image_url='"><script>alert(1)</script>')
+        self.assertNotIn('<script>', html)
+
     def test_title_section(self):
         html = self.render([{'type': 'title', 'text': {'es': 'Materiales'}}])
         self.assertIn('<h3 class="text-[1.125em] font-bold mt-2 mb-1 text-[var(--accent-color)]">Materiales</h3>', html)
diff --git a/crochet/tests/test_views.py b/crochet/tests/test_views.py
index f39d44a..a4e3187 100644
--- a/crochet/tests/test_views.py
+++ b/crochet/tests/test_views.py
@@ -1,7 +1,9 @@
 import json
+import os
 import re
 
 from django.contrib.auth.models import User
+from django.core.files.uploadedfile import SimpleUploadedFile
 from django.test import TestCase
 from django.urls import reverse
 from django.utils import translation
@@ -61,6 +63,18 @@ class PatternEditViewTests(TestCase):
 
         self.assertEqual(response.status_code, 404)
 
+    def test_cover_image_large_url_is_available_to_the_live_preview(self):
+        self.pattern.cover_image_large.save(
+            'large.jpg', make_test_image_file(name='large.jpg'), save=True,
+        )
+        self.client.force_login(self.owner)
+        with translation.override('es'):
+            url = reverse('crochet:pattern_edit', args=[self.pattern.uuid])
+        response = self.client.get(url)
+
+        self.assertContains(response, 'id="cover-image-large-url"')
+        self.assertContains(response, f'value="{self.pattern.cover_image_large.url}"')
+
     def test_anonymous_user_is_redirected_to_login(self):
         with translation.override('es'):
             url = reverse('crochet:pattern_edit', args=[self.pattern.uuid])
@@ -110,6 +124,18 @@ class PatternDetailViewTests(TestCase):
         self.assertContains(response, 'Ampharos')
         self.assertContains(response, '3 Punto bajo')
 
+    def test_cover_image_renders_below_title(self):
+        self.pattern.cover_image_large.save(
+            'large.jpg', make_test_image_file(name='large.jpg'), save=True,
+        )
+        with translation.override('es'):
+            url = reverse('crochet:pattern_detail', args=[self.pattern.uuid])
+        response = self.client.get(url)
+        body = response.content.decode()
+
+        self.assertContains(response, f'<img src="{self.pattern.cover_image_large.url}"')
+        self.assertLess(body.index('Ampharos'), body.index(self.pattern.cover_image_large.url))
+
     def test_page_has_no_editable_elements(self):
         with translation.override('es'):
             url = reverse('crochet:pattern_detail', args=[self.pattern.uuid])
@@ -291,6 +317,73 @@ class PatternImageUploadViewTests(TestCase):
         self.assertEqual(response.status_code, 403)
 
 
+class PatternCoverImageUploadViewTests(TestCase):
+    def setUp(self):
+        self.owner = User.objects.create_user(username='crocheter', password='a-very-uncommon-pw-1')
+        self.pattern = Pattern.objects.create(created_by=self.owner)
+        self.client.force_login(self.owner)
+        with translation.override('es'):
+            self.url = reverse('crochet:pattern_cover_upload', args=[self.pattern.uuid])
+
+    def test_uploads_and_generates_variants(self):
+        response = self.client.post(self.url, data={'cover_image': make_test_image_file()})
+
+        self.assertEqual(response.status_code, 200)
+        data = response.json()
+        self.assertIn('thumbnailUrl', data)
+        self.assertIn('largeUrl', data)
+        self.pattern.refresh_from_db()
+        self.assertTrue(self.pattern.cover_image)
+        self.assertTrue(self.pattern.cover_image_thumbnail)
+        self.assertTrue(self.pattern.cover_image_large)
+
+    def test_replacing_cover_deletes_previous_files(self):
+        self.client.post(self.url, data={'cover_image': make_test_image_file(name='first.png')})
+        self.pattern.refresh_from_db()
+        old_original_path = self.pattern.cover_image.path
+        old_thumbnail_path = self.pattern.cover_image_thumbnail.path
+        old_large_path = self.pattern.cover_image_large.path
+
+        self.client.post(self.url, data={'cover_image': make_test_image_file(name='second.png')})
+        self.pattern.refresh_from_db()
+
+        # cover_image conserva el nombre subido (cambia de "first.png" a
+        # "second.png"), así que el archivo antiguo debe desaparecer.
+        self.assertFalse(os.path.exists(old_original_path))
+        # cover_image_thumbnail/large usan un nombre fijo (thumbnail.jpg/
+        # large.jpg, ver cover_image.py): si nada más lo había reclamado ya,
+        # la segunda subida sobrescribe la misma ruta (no cambia); si sí
+        # cambia (otro patrón se quedó con ese nombre primero, ver la
+        # carpeta compartida por mes), la ruta antigua debe desaparecer. En
+        # ningún caso debe quedar huérfana.
+        if self.pattern.cover_image_thumbnail.path != old_thumbnail_path:
+            self.assertFalse(os.path.exists(old_thumbnail_path))
+        if self.pattern.cover_image_large.path != old_large_path:
+            self.assertFalse(os.path.exists(old_large_path))
+
+    def test_missing_file_returns_bad_request(self):
+        response = self.client.post(self.url, data={})
+        self.assertEqual(response.status_code, 400)
+
+    def test_invalid_image_returns_bad_request(self):
+        invalid_file = SimpleUploadedFile('not-an-image.png', b'not an image', content_type='image/png')
+        response = self.client.post(self.url, data={'cover_image': invalid_file})
+        self.assertEqual(response.status_code, 400)
+
+    def test_other_user_gets_403(self):
+        User.objects.create_user(username='other', password='a-very-uncommon-pw-1')
+        self.client.login(username='other', password='a-very-uncommon-pw-1')
+        response = self.client.post(self.url, data={'cover_image': make_test_image_file()})
+        self.assertEqual(response.status_code, 403)
+
+    def test_pattern_without_owner_is_blocked_even_for_logged_in_user(self):
+        orphan_pattern = Pattern.objects.create()
+        with translation.override('es'):
+            url = reverse('crochet:pattern_cover_upload', args=[orphan_pattern.uuid])
+        response = self.client.post(url, data={'cover_image': make_test_image_file()})
+        self.assertEqual(response.status_code, 403)
+
+
 class PatternDeleteViewTests(TestCase):
     def setUp(self):
         self.owner = User.objects.create_user(username='crocheter', password='a-very-uncommon-pw-1')
diff --git a/crochet/urls.py b/crochet/urls.py
index 2292a55..2974346 100644
--- a/crochet/urls.py
+++ b/crochet/urls.py
@@ -5,6 +5,7 @@ from django.utils.translation import gettext_lazy as _
 from crochet.forms import StyledAuthenticationForm
 from crochet.views import (
     AccountHomeView,
+    PatternCoverImageUploadView,
     PatternCreateView,
     PatternDeleteView,
     PatternDetailView,
@@ -31,6 +32,7 @@ urlpatterns = [
     path(_('pattern/<uuid:uuid>/edit/'), name='pattern_edit', view=PatternEditView.as_view()),
     path(_('pattern/<uuid:uuid>/save/'), name='pattern_save', view=PatternSaveView.as_view()),
     path(_('pattern/<uuid:uuid>/images/'), name='pattern_image_upload', view=PatternImageUploadView.as_view()),
+    path(_('pattern/<uuid:uuid>/cover/'), name='pattern_cover_upload', view=PatternCoverImageUploadView.as_view()),
     path(_('pattern/<uuid:uuid>/pdf/'), name='pattern_pdf', view=PatternPdfView.as_view()),
     path(_('pattern/<uuid:uuid>/delete/'), name='pattern_delete', view=PatternDeleteView.as_view()),
     path(_('pattern/new/'), name='pattern_create', view=PatternCreateView.as_view()),
diff --git a/crochet/views.py b/crochet/views.py
index 26ff6c7..0adcbef 100644
--- a/crochet/views.py
+++ b/crochet/views.py
@@ -13,6 +13,7 @@ from django.utils.translation import get_language, gettext_lazy as _
 from django.views import View
 from django.views.generic import CreateView, DetailView, TemplateView
 
+from crochet.cover_image import InvalidCoverImage, build_cover_image_variants
 from crochet.forms import StyledUserCreationForm
 from crochet.models import Pattern, PatternImage, StitchType
 from crochet.pattern_render import render_pattern_html, sanitize_page_settings
@@ -57,6 +58,7 @@ def _pattern_detail_context(pattern):
         'page_settings': page_settings,
         'rendered_pattern': render_pattern_html(
             pattern.sections, page_settings, lang, _stitch_types_data(), PATTERN_EMPTY_MESSAGE,
+            cover_image_url=pattern.cover_image_large.url if pattern.cover_image_large else None,
         ),
     }
 
@@ -193,6 +195,38 @@ class PatternImageUploadView(View):
         return JsonResponse({'id': pattern_image.id, 'url': pattern_image.image.url})
 
 
+class PatternCoverImageUploadView(View):
+    # Mismo motivo que en PatternSaveView: lo llama cover-image.js por fetch.
+    def post(self, request, uuid):
+        pattern = _get_owned_pattern_or_403(request, uuid)
+
+        uploaded_file = request.FILES.get('cover_image')
+        if not uploaded_file:
+            return HttpResponseBadRequest('Falta el archivo "cover_image"')
+
+        try:
+            original, thumbnail, large = build_cover_image_variants(uploaded_file)
+        except InvalidCoverImage as error:
+            return HttpResponseBadRequest(str(error))
+
+        # Reemplaza los archivos anteriores en vez de acumularlos: cada
+        # patrón tiene una única portada vigente.
+        for field_name, content_file in (
+            ('cover_image', original), ('cover_image_thumbnail', thumbnail), ('cover_image_large', large),
+        ):
+            field_file = getattr(pattern, field_name)
+            if field_file:
+                field_file.delete(save=False)
+            field_file.save(content_file.name, content_file, save=False)
+
+        pattern.save(update_fields=['cover_image', 'cover_image_thumbnail', 'cover_image_large'])
+
+        return JsonResponse({
+            'thumbnailUrl': pattern.cover_image_thumbnail.url,
+            'largeUrl': pattern.cover_image_large.url,
+        })
+
+
 class RegisterView(CreateView):
     # UserCreationForm ya pide justo nombre de usuario + contraseña (dos
     # veces, para confirmarla): no hace falta un formulario propio, solo la